Sharrow Props Do It Again—Dramatic Efficiency Boost on Regal 38 w/ 3x Yamaha 300’s

The Regal 38 SAV is a fishing/diving/weekending platform that scales about 18,800 lb (kg) dry and is rated for a maximum of 900-hp. Sharrow Marine tested her with triple 300 Yamaha’s, first equipped with stock Yamaha SWS II 15.25” x 18” stainless steel three blade propellers, then with Sharrow 15.5” x 17” TrueAdvance stainless steel props. This report is based on numbers they have supplied.

As we have come to expect in these tests, the Sharrow propellers proved superior throughout the middle ranges in both speed and efficiency or fuel economy. 

The Sharrow’s were superior in MPG at every speed from idle up to the mid-30’s. At displacement speeds she is up to 47% more fuel efficient.  This advantage under 10 mph would also be particularly significant for boats used in offshore trolling, where low speeds are maintained for hours.

The “advance rate” is a measure of efficiency of a propeller linked to the pitch. This chart shows that the Sharrow propellers approach their designated pitch at lower rpm, with an advantage maxing out at 80% better than the conventional props at 3000 rpm, 40% better at 3500, in the range where offshore boats commonly operate in choppy seas. 

Propeller efficiency is also superior with the Sharrow TrueAdvance propellers, some 92% better than the conventional propellers at 3000 rpm as shown here, maintaining an 11 percent edge up to 4000 rpm before easing into pretty much a dead heat with the SWS models at WOT.

Propeller slip is a measure of how much a propeller actually advances on each revolution compared to how much it would advance if it were “screwing” through a solid like wood. Less slip means better performance and lower fuel use. 

The stock propellers, as seen here, had 130% more slip at 3000 rpm, 187% more slip at 3500 and 82 % more at 4000 rpm.

When it comes to speed, Sharrow TrueAdvance propellers also showed a significant advantage in the mid-range from 3000 to 3500. The Sharrow’s pushed the boat to 20.2 mph at 3000 rpm while the standard propellers were still wallowing along at 11.2 mph. This is important because it means that boat will get on plane at least 500 rpm sooner than it would with standard props. 

At 3500, the standard propellers start to pick up speed as the boat goes over the hump, attaining 19.5 mph, but by that point the Sharrow’s are already purring along at 27.3 mph, 40% better. The advantage fades at higher rpm, and the stock props were slightly faster at WOT. Most standard props are designed to be most efficient at WOT -- but who drives their boat there for more than a few minutes?

Bottom line is, in this test as so many others, Sharrow TrueAdvance propellers show a surprising superiority in both mid-range speed and fuel efficiency. Users say they also make most boats much easier to handle around the docks, with more positive steering and a stronger reverse, and that they run considerably quieter and with less vibration than standard propellers when the boat is on plane.